Heart valve disease is a serious problem that involves the malfunction of one or more valves of the heart. The malfunction can manifest itself in a variety of manners. For example, valve stenosis is the calcification or narrowing of a native heart valve. As a result, the native heart valve is not able to completely open and blood flow through the native valve is impeded or restricted. Another example of heart valve disease is valve insufficiency. Valve insufficiency is the failure of a native heart valve to close properly to prevent leaking, or backflow, of blood through the valve.
Various methods have been developed to treat heart valve disease. Some of these methods require a balloon member that is expanded within the native heart valve. For example, a balloon member can be used in a valvuloplasty procedure where the balloon member is positioned within the native heart valve and expanded to increase the opening size (i.e., flow area) of the native heart valve and thereby improve blood flow. Another procedure that can be performed is a valve replacement, in which a native heart valve is replaced by an artificial heart valve. The implantation of an artificial heart valve in the heart can also involve the expansion of a balloon member in the valve annulus. For example, the balloon member can be used to increase the size of the native valve prior to implantation of the artificial valve and/or it can be used to expand and deploy the artificial valve itself.
Currently, a single balloon is typically used to deploy the heart valve or stent minimally invasive cardiovascular procedures. The expansion of a balloon member within a native valve or other vascular passageway, however, can temporarily block or restrict blood flow through the passageway. Furthermore, in the case of valve replacement, the positioning of the artificial heart valve may be complicated by the buildup of pressure in the left ventricle. For example, the blocked blood flow will create a strong force against the balloon while the heart is still pumping during the procedure, decreasing the stability of the implant and making it difficult to position the heart valve. Accordingly, valvuloplasty and valve replacement procedures, and other similar procedures which utilize expandable balloon members, must generally be performed quickly so that the balloon member is inflated for only a brief period. Rapid ventricular pacing procedures may be employed to increase the stability, but this procedure can only be carried out for a limited time span.
Accordingly, a need exists for improved devices that enable the patient's blood to flow through the passageway while the procedure is taking place. Such devices would increase the precision of device placement and reduce the risk of injury to the patient.